Planetary gear alignment and indexing method and associated tool

Abstract

A method is disclosed for assembly of a planetary gear drive, wherein the gear drive includes a ring gear, a sun gear, and a plurality of planet gears engaged with the ring gear and sun gear. The method includes mounting the planet gears within a carrier, with the planet gears freely rotatable relative to the carrier. A gear alignment tool is inserted through a bore in a front face of the carrier and is used to index the planet gears into an aligned rotational position for proper subsequent engagement with the ring gear and sun gear.

What is claimed is: 
     
       1. A method for assembly of a planetary gear drive, wherein the gear drive includes a ring gear, a sun gear, and a plurality of planet gears engaged with the ring gear and sun gear, the method comprising:
 mounting the planet gears on bearings within a carrier, the planet gears freely rotatable relative to the carrier; 
 inserting a gear alignment tool through a bore in a front face of the carrier to a central position within the carrier equidistant to the planet gears, the tool including an elongated handle having a sufficient length to pass through the bore and a plurality of engagement fingers oriented in a first longitudinal position that allows the tool to slide through the bore, the engagement fingers residing within a cage structure at an end of the handle in the first longitudinal position, the engagement fingers having a first end pivotally mounted to the cage structure and a second free end that is radially movable away from the cage structure to engage the planet gears; 
 with the tool, radially spreading the engagement fingers from the central position such that the engagement fingers index the planet gears into an aligned rotational position for proper subsequent engagement with the ring gear and sun gear; and 
 with the planet gears properly indexed and maintained in position with the tool, mounting the carrier onto a casing of the gear drive so that the planet gears engage the ring gear and sun gear. 
 
     
     
       2. The method as in  claim 1 , wherein the fingers include an elongated slot engaged by a pin in the cage structure, wherein in the fingers are caused to radially spread by axially advancing the cage into the central position while preventing axial movement of the fingers thereby causing the free ends of the fingers to radially spread as a result of relative movement of the pins within the respective slots. 
     
     
       3. The method as in  claim 2 , wherein the tool is manually advanced through the carrier and the axial movement of the fingers is manually prevented. 
     
     
       4. The method as in  claim 1 , wherein the tool is removed from the carrier prior to or during mounting of the carrier onto the casing. 
     
     
       5. An alignment and indexing tool for assembly of a planetary gear drive, wherein a carrier housing having a plurality of planet gears mounted therein is to be mounted onto a gear casing for subsequent engagement with a ring gear and a sun gear, said tool comprising:
 an elongated handle having a sufficient length to pass through a bore in the carrier housing to a central position within said carrier equidistant to the planet gears; 
 a plurality of engagement fingers mounted to an end of said handle, said engagement fingers oriented in a first longitudinal position relative to said handle that allows said tool to slide through the bore and into the carrier housing; 
 said engagement fingers radially spreadable relative to said handle from said first longitudinal position to a spread position wherein said engagement fingers engage and index the planet gears to an aligned rotational position for proper subsequent engagement with the ring gear and sun gear upon mounting the carrier onto the gear casing, 
 wherein said engagement fingers reside within a cage structure at an end of said handle in said first longitudinal position, said engagement fingers having a first end pivotally mounted to said cage structure and a second free end that is radially movable away from said cage structure to engage the planet gears. 
 
     
     
       6. The alignment and indexing tool as in  claim 5 , comprising three of said engagement fingers rotationally spaced 120 degrees apart on said handle, wherein said tool is configured for indexing three planet gears within the carrier. 
     
     
       7. The alignment and indexing tool as in  claim 5 , wherein said engagement fingers include an elongated slot engaged by a pin in said cage structure, wherein said engagement fingers are caused to radially spread by axial movement of said cage structure into the central position while preventing axial movement of said free ends of said engagement fingers. 
     
     
       8. The alignment and indexing tool as in  claim 7 , wherein said engagement fingers are movable from said radially expanded position to said first longitudinal position upon withdrawing said handle from said carrier.